The present invention generally relates to improvements in a fluid pressure regulator, and more particularly relates to an improved fluid pressure regulator used within a fluid control system.
Pressurized fluid containers, such as gas containers or cylinders, have been used for many applications. For example, cylinders storing high-pressure hydrides have been used in semiconductor manufacturing processes. Typically, the high-pressure fluid, such as a gas, stored in fluid cylinders is not dispensed at high pressure. Rather, a pressure regulator or other flow restriction device used in conjunction with a cylinder typically delivers, or dispenses, the fluid from the cylinder at a pressure substantially lower than that inside the cylinder. Typically, a self-regulating mechanical device, or pressure regulator, is used to reduce the pressure of a dispensed gas. Most, if not all, pressure regulators incorporate a diaphragm or a piston connected to a valve as a way of reducing the pressure of the dispensed gas.
Typically, a pressure regulator is discrete from the fluid cylinder and from the valve that selectively controls the dispensing of the gas from the cylinder. Gas under high pressure, however, may escape at a dangerously high rate from a fluid cylinder if the cylinder valve is inadvertently opened. To minimize the risks associated with gas leaks, some gas dispensing systems have included pressure reduction devices, such as a restrictive flow orifice or an integrated valve, as part of the cylinder assembly. An integrated valve typically includes a low-pressure shut-off valve and a pressure regulator within the same fluid dispensing assembly.
A pressure regulator may be set to reduce the pressure of a gas to subatmospheric pressure, i.e., less than 1 bar absolute pressure. A fluid dispensing, or fluid control, system utilizing a subatmospheric pressure regulator offers a safety advantage. That is, gas is not dispensed from the system, even if the cylinder valve is opened, unless the pressure on the downstream side of the pressure regulator is lower than atmospheric pressure. In other words, gas is dispensed from the system only when a downstream device or condition draws the gas from a fluid outlet of the dispensing assembly, i.e., by drawing a vacuum. The method of actively extracting gas from a dispensing assembly of a gas dispensing system is used in, for example, self-contained underwater breathing apparatus (“SCUBA”) and in systems designed to supply hazardous toxic gases to semiconductor manufacturing systems.
Positioning an integrated valve substantially or entirely within a fluid cylinder protects the pressure regulator of the integrated valve from external forces and damage associated with moving the cylinder. Further, installing an integrated valve within a fluid cylinder makes the gas dispensing system more compact and easier to handle.
U.S. Pat. No. 6,101,816 issued to Wang et al. (“Wang I”) (assigned to Advanced Technology Materials, Inc), granted Aug. 15, 2000, teaches a fluid pressure regulator positioned within a fluid cylinder. The invention described in Wang I, however, includes a pressure regulator located upstream from any valves included within the system. Fluid contained in the fluid cylinder or vessel flows through the pressure regulator before flowing through any valve or through any other flow control element within the system. Wang I, however, does not disclose the size of the opening of the cylinder or vessel used with the invention. Pressure regulators conventionally used with toxic gases, however, do not easily fit inside standard fluid cylinders. Typically, standard fluid cylinders include an opening of ¾ inch NGT (National Gas Taper), which is approximately 23 mm in diameter. However, the smallest gas pressure regulators commercially available for use with such applications are approximately 40 mm in diameter.
U.S. Pat. No. 6,089,027, also issued to Wang et al, (“Wang II”) (also assigned to Advanced Technology Materials, Inc.) and granted Jul. 18, 2000, also teaches a fluid pressure regulator disposed within a fluid cylinder or vessel. Wang II states at column 4, lines 55–59, “In order to usefully exploit the Wang et al. system of the parent application [Wang I], embodying a ‘regulator in a bottle’ approach, larger cylinder inlets are required than are conventionally available.” Further, at column 5, lines 3–11, Wang II states, “In order to commercially enable the Wang et al. ‘regulator in a bottle’ approach of the parent patent application, it is necessary to provide a cylinder that satisfies United States Department of Transportation (USDOT) packaging standards, has a larger inlet opening than is conventionally available, and can withstand pressures in the range of from about 1000 to about 5000 pounds per square inch (psi). No such vessel has been proposed or fabricated by the prior art, and none is commercially available.” Thus, while Wang I does not specify the size of the opening of the cylinder or vessel, Wang II clarifies that the invention described in Wang I cannot be used with standard fluid cylinders. Further, Wang II teaches a cylinder having an inlet opening of greater than 1 inch NGT.
As compared to standard fluid cylinders having a ¾ inch NGT opening, fluid cylinders having an opening greater than the standard ¾ inch NGT, such as those used with Wang I and Wang II, are more prone to leaks, are heavier, and are more expensive to manufacture. The cylinder openings of standard fluid cylinders are, for reasons of weight, containment integrity and manufacturing cost, made as small as possible. Further, a large number of standard fluid cylinders already exist. The regulators described in Wang I and Wang II, however, cannot be used with these standard cylinders.
European Patent Application 0 512 553 A1 (“MEVA application”), published Nov. 11, 1992 is directed to a superatmospheric pressure controlled reducing valve. The MEVA application, at column 2, lines 56 to Col. 3, lines 1–2 states, “The valve designed for being used in respirators adapted to operate exclusively in the superatmospheric pressure breathing regime is controlled by a straight stay or stays immediately confining a space or cavity.” The MEVA application shows a valve that is pulled against a fluid inlet through the bending of stays. However, the MEVA application does not teach or suggest the use of the superatmospheric pressure controlled reducing valve with a semiconductor manufacturing system, or with toxic gases. Rather, as discussed in the MEVA abstract and at Col. 2, lines 56 to Col. 3, lines 1–2, the reducing valve described in the MEVA application is used “exclusively in the superatmospheric pressure breathing regime.” Further the MEVA application does not teach or suggest positioning, or interiorly disposing, the superatmospheric pressure controlled reducing valve within a fluid cylinder.
Thus a need exists for a system and method of efficiently and inexpensively protecting a fluid pressure regulator that is used with a standard fluid cylinder having an opening of ¾ inch NGT. Further, a need exists for a system and method of protecting a fluid pressure regulator that is used with a standard fluid cylinder that stores toxic gases, such as hydrides used in the semiconductor manufacturing industry.